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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>LLVM seems to be generating way too complex of branching
based on the short-circuit optimization. The code in question is as follows:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>define void @ test_fc_while_and(float %x, float %y, float
addrspace(11)* %result) nounwind {<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>entry:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> %tobool3 = fcmp
une float %x,
0.000000e+000
; <i1> [#uses=1]<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> %tobool24 = fcmp
une float %y,
0.000000e+000
; <i1> [#uses=2]<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> %or.cond5 = and
i1 %tobool3, %tobool24 ;
<i1> [#uses=1]<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> <b><span
style='font-weight:bold'>br i1 %or.cond5, label %bb.nph, label %whileexit<o:p></o:p></span></b></span></font></p>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'><o:p> </o:p></span></font></b></p>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>bb.nph:
; preds = %entry<o:p></o:p></span></font></b></p>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'> br
i1 %tobool24, label %whilebody.us, label %whilebody<o:p></o:p></span></font></b></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>whilebody.us:
; preds = %whilebody.us, %bb.nph<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>…code here…<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> br i1 %phitmp,
label %whilebody.us, label %whileexit<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>whilebody:
; preds = %bb.nph<o:p></o:p></span></font></b></p>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>…code here…<o:p></o:p></span></font></b></p>
<p class=MsoNormal><b><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial;font-weight:bold'>
br label %whileexit<o:p></o:p></span></font></b></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>whileexit:
; preds = %whilebody, %whilebody.us, %entry<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> %z.0.lcssa = phi
float [ 0.000000e+000, %entry ], [ %add, %whilebody ], [ %add.us, %whilebody.us
]
; <float> [#uses=1]<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> store float
%z.0.lcssa, float addrspace(11)* %result<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> ret void<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>}<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>based on original code of:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>void test_fc_while_and(float x, float y, float* result)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>{<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> float z =
(float)0;<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> <b><span
style='font-weight:bold'>while (x && y)</span></b> {<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'> </span></font><font
size=2 face=Arial><span lang=PL style='font-size:10.0pt;font-family:Arial'>z +=
(x * y);<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=PL style='font-size:10.0pt;
font-family:Arial'> ++x<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=PL style='font-size:10.0pt;
font-family:Arial'> }<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span lang=PL style='font-size:10.0pt;
font-family:Arial'> *result = z;<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>}<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Now the problem issue is with the bolded code. The two
comparisons and the and instruction that are mapped to the bolded while
statement. What I am trying to figure out why the bb.nph branch is even
required and how do I disable it from being generated? The first branch
instruction handles correctly the condition that I wanted, so there should be
no reason that bb.nph is generated. The same for whilebody, as it shouldn’t
be there.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Any ideas?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Thanks,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Micah Villmow<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Systems Engineer<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Advanced Technology & Performance<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Advanced Micro Devices Inc.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><ns0:Street w:insAuthor="Micah Villmow"
w:insDate="2008-10-01T13:11:00Z" w:endInsAuthor="Micah Villmow"
w:endInsDate="2008-10-01T13:11:00Z"><ns0:address w:insAuthor="Micah Villmow"
w:insDate="2008-10-01T13:11:00Z" w:endInsAuthor="Micah Villmow"
w:endInsDate="2008-10-01T13:11:00Z"><st1:Street w:st="on"><st1:address w:st="on">4555
Great America Pkwy</st1:address></st1:Street></ns0:address></ns0:Street>,<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><ns0:place w:insAuthor="Micah Villmow"
w:insDate="2008-10-01T13:11:00Z" w:endInsAuthor="Micah Villmow"
w:endInsDate="2008-10-01T13:11:00Z"><ns0:City w:insAuthor="Micah Villmow"
w:insDate="2008-10-01T13:11:00Z" w:endInsAuthor="Micah Villmow"
w:endInsDate="2008-10-01T13:11:00Z"><st1:City w:st="on"><st1:place w:st="on">Santa
Clara</st1:place></st1:City></ns0:City></ns0:place>, CA. 95054<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>P: 408-572-6219<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>F: 408-572-6596</span></font><font size=2 face=Arial><span
style='font-size:10.0pt;font-family:Arial'><o:p></o:p></span></font></p>
<p class=MsoNormal><font size=3 face="Times New Roman"><span style='font-size:
12.0pt'><o:p> </o:p></span></font></p>
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